The present invention concerns a device for axial shifting of oscillating rollers in a printing machine.
The devices used up to now in printing machines, for instance for offset printing, and which allow an axial shifting of oscillating rollers, are generally mechanically based, for instance on the principle of connecting rods with an eccentric or a similar device. These devices representing the state of the art all have the drawback that they do not allow, or only allow with difficulty, the realization of a centralized remote-control for the following settings:
adaptation of the movement of every oscillating roller to various printing sizes;
setting of the reversing point (which corresponds actually to the location where a very large rotation of the distributing cylinder is to take place with respect to the axial shifting of the corresponding oscillating roller) with reference to the position of the printing plate;
setting of the speed curve and of the range of the axial movement carried out by each oscillating roller.
Moreover, all the settings mentioned above are to be carried out at standstill in order to provide the operator with access to the machine area where the system with the connecting rod and the eccentric is located. Furthermore, a device with a connecting rod and an eccentric results almost in a sinusoidal curve of the shifting speed of the oscillating roller. Similarly, the shifting frequency of the oscillating roller is given by the kinematic chain of the machine.